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# Equalizer

`public class Equalizer`
`` `extends AudioEffect` ``

java.lang.Object
↳ | android.media.audiofx.AudioEffect
| ↳ | android.media.audiofx.Equalizer

An Equalizer is used to alter the frequency response of a particular music source or of the main output mix.

An application creates an Equalizer object to instantiate and control an Equalizer engine in the audio framework. The application can either simply use predefined presets or have a more precise control of the gain in each frequency band controlled by the equalizer.

The methods, parameter types and units exposed by the Equalizer implementation are directly mapping those defined by the OpenSL ES 1.0.1 Specification (http://www.khronos.org/opensles/) for the SLEqualizerItf interface. Please refer to this specification for more details.

To attach the Equalizer to a particular AudioTrack or MediaPlayer, specify the audio session ID of this AudioTrack or MediaPlayer when constructing the Equalizer.

NOTE: attaching an Equalizer to the global audio output mix by use of session 0 is deprecated.

See `MediaPlayer.getAudioSessionId()` for details on audio sessions.

See `AudioEffect` class for more details on controlling audio effects.

## Summary

### Nested classes
`interface` | `Equalizer.OnParameterChangeListener` The OnParameterChangeListener interface defines a method called by the Equalizer when a parameter value has changed.
`class` | `Equalizer.Settings` The Settings class regroups all equalizer parameters.

### Constants
`int` | `PARAM_BAND_FREQ_RANGE` Band frequency range.
`int` | `PARAM_BAND_LEVEL` Band level.
`int` | `PARAM_CENTER_FREQ` Band center frequency.
`int` | `PARAM_CURRENT_PRESET` Current preset.
`int` | `PARAM_GET_BAND` Band for a given frequency.
`int` | `PARAM_GET_NUM_OF_PRESETS` Request number of presets.
`int` | `PARAM_GET_PRESET_NAME` Request preset name.
`int` | `PARAM_LEVEL_RANGE` Band level range.
`int` | `PARAM_NUM_BANDS` Number of bands.
`int` | `PARAM_STRING_SIZE_MAX` Maximum size for preset name

### Inherited constants
From class `android.media.audiofx.AudioEffect`
`String` | `ACTION_CLOSE_AUDIO_EFFECT_CONTROL_SESSION` Intent to signal to the effect control application or service that an audio session is closed and that effects should not be applied anymore.
`String` | `ACTION_DISPLAY_AUDIO_EFFECT_CONTROL_PANEL` Intent to launch an audio effect control panel UI.
`String` | `ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION` Intent to signal to the effect control application or service that a new audio session is opened and requires audio effects to be applied.
`int` | `ALREADY_EXISTS` Internal operation status.
`int` | `CONTENT_TYPE_GAME` Value for `EXTRA_CONTENT_TYPE` when the type of content played is game audio
`int` | `CONTENT_TYPE_MOVIE` Value for `EXTRA_CONTENT_TYPE` when the type of content played is video or movie
`int` | `CONTENT_TYPE_MUSIC` Value for `EXTRA_CONTENT_TYPE` when the type of content played is music
`int` | `CONTENT_TYPE_VOICE` Value for `EXTRA_CONTENT_TYPE` when the type of content played is voice audio
`String` | `EFFECT_AUXILIARY` Effect connection mode is auxiliary.
`String` | `EFFECT_INSERT` Effect connection mode is insert.
`String` | `EFFECT_POST_PROCESSING` Effect connection mode is post processing.
`String` | `EFFECT_PRE_PROCESSING` Effect connection mode is pre processing.
`int` | `ERROR` Unspecified error.
`int` | `ERROR_BAD_VALUE` Operation failed due to bad parameter value.
`int` | `ERROR_DEAD_OBJECT` Operation failed due to dead remote object.
`int` | `ERROR_INVALID_OPERATION` Operation failed because it was requested in wrong state.
`int` | `ERROR_NO_INIT` Operation failed due to bad object initialization.
`int` | `ERROR_NO_MEMORY` Operation failed due to lack of memory.
`String` | `EXTRA_AUDIO_SESSION` Contains the ID of the audio session the effects should be applied to.
`String` | `EXTRA_CONTENT_TYPE` Indicates which type of content is played by the application.
`String` | `EXTRA_PACKAGE_NAME` Contains the package name of the calling application.
`int` | `SUCCESS` Successful operation.

### Inherited fields
From class `android.media.audiofx.AudioEffect`
`public static final UUID` | `EFFECT_TYPE_AEC` UUID for Acoustic Echo Canceler (AEC)
`public static final UUID` | `EFFECT_TYPE_AGC` UUID for Automatic Gain Control (AGC)
`public static final UUID` | `EFFECT_TYPE_BASS_BOOST` UUID for bass boost effect
`public static final UUID` | `EFFECT_TYPE_DYNAMICS_PROCESSING` UUID for Dynamics Processing
`public static final UUID` | `EFFECT_TYPE_ENV_REVERB` UUID for environmental reverberation effect
`public static final UUID` | `EFFECT_TYPE_EQUALIZER` UUID for equalizer effect
`public static final UUID` | `EFFECT_TYPE_LOUDNESS_ENHANCER` UUID for Loudness Enhancer
`public static final UUID` | `EFFECT_TYPE_NS` UUID for Noise Suppressor (NS)
`public static final UUID` | `EFFECT_TYPE_PRESET_REVERB` UUID for preset reverberation effect
`public static final UUID` | `EFFECT_TYPE_VIRTUALIZER` UUID for virtualizer effect

### Public constructors
`Equalizer(int priority, int audioSession)` Class constructor.

### Public methods
`short` | `getBand(int frequency)` Gets the band that has the most effect on the given frequency.
`int[]` | `getBandFreqRange(short band)` Gets the frequency range of the given frequency band.
`short` | `getBandLevel(short band)` Gets the gain set for the given equalizer band.
`short[]` | `getBandLevelRange()` Gets the level range for use by `setBandLevel(short, short)`.
`int` | `getCenterFreq(short band)` Gets the center frequency of the given band.
`short` | `getCurrentPreset()` Gets current preset.
`short` | `getNumberOfBands()` Gets the number of frequency bands supported by the Equalizer engine.
`short` | `getNumberOfPresets()` Gets the total number of presets the equalizer supports.
`String` | `getPresetName(short preset)` Gets the preset name based on the index.
`Equalizer.Settings` | `getProperties()` Gets the equalizer properties.
`void` | `setBandLevel(short band, short level)` Sets the given equalizer band to the given gain value.
`void` | `setParameterListener(Equalizer.OnParameterChangeListener listener)` Registers an OnParameterChangeListener interface.
`void` | `setProperties(Equalizer.Settings settings)` Sets the equalizer properties.
`void` | `usePreset(short preset)` Sets the equalizer according to the given preset.

### Inherited methods
From class `android.media.audiofx.AudioEffect`
`void` | `finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`AudioEffect.Descriptor` | `getDescriptor()` Get the effect descriptor.
`boolean` | `getEnabled()` Returns effect enabled state
`int` | `getId()` Returns effect unique identifier.
`boolean` | `hasControl()` Checks if this AudioEffect object is controlling the effect engine.
`static Descriptor[]` | `queryEffects()` Query all effects available on the platform.
`void` | `release()` Releases the native AudioEffect resources.
`void` | `setControlStatusListener(AudioEffect.OnControlStatusChangeListener listener)` Sets the listener AudioEffect notifies when the effect engine control is taken or returned.
`void` | `setEnableStatusListener(AudioEffect.OnEnableStatusChangeListener listener)` Sets the listener AudioEffect notifies when the effect engine is enabled or disabled.
`int` | `setEnabled(boolean enabled)` Enable or disable the effect.
From class `java.lang.Object`
`Object` | `clone()` Creates and returns a copy of this object.
`boolean` | `equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void` | `finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>` | `getClass()` Returns the runtime class of this `Object`.
`int` | `hashCode()` Returns a hash code value for the object.
`final void` | `notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void` | `notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String` | `toString()` Returns a string representation of the object.
`final void` | `wait(long timeout, int nanos)` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
`final void` | `wait(long timeout)` Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.
`final void` | `wait()` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.

## Constants

### PARAM_BAND_FREQ_RANGE

    public static final int PARAM_BAND_FREQ_RANGE

Band frequency range. Parameter ID for `Equalizer.OnParameterChangeListener`

Constant Value: 4 (0x00000004)

### PARAM_BAND_LEVEL

    public static final int PARAM_BAND_LEVEL

Band level. Parameter ID for OnParameterChangeListener

Constant Value: 2 (0x00000002)

### PARAM_CENTER_FREQ

    public static final int PARAM_CENTER_FREQ

Band center frequency. Parameter ID for OnParameterChangeListener

Constant Value: 3 (0x00000003)

### PARAM_CURRENT_PRESET

    public static final int PARAM_CURRENT_PRESET

Current preset. Parameter ID for OnParameterChangeListener

Constant Value: 6 (0x00000006)

### PARAM_GET_BAND

    public static final int PARAM_GET_BAND

Band for a given frequency. Parameter ID for OnParameterChangeListener

Constant Value: 5 (0x00000005)

### PARAM_GET_NUM_OF_PRESETS

    public static final int PARAM_GET_NUM_OF_PRESETS

Request number of presets. Parameter ID for OnParameterChangeListener

Constant Value: 7 (0x00000007)

### PARAM_GET_PRESET_NAME

    public static final int PARAM_GET_PRESET_NAME

Request preset name. Parameter ID for OnParameterChangeListener

Constant Value: 8 (0x00000008)

### PARAM_LEVEL_RANGE

    public static final int PARAM_LEVEL_RANGE

Band level range. Parameter ID for OnParameterChangeListener

Constant Value: 1 (0x00000001)

### PARAM_NUM_BANDS

    public static final int PARAM_NUM_BANDS

Number of bands. Parameter ID for OnParameterChangeListener

Constant Value: 0 (0x00000000)

### PARAM_STRING_SIZE_MAX

    public static final int PARAM_STRING_SIZE_MAX

Maximum size for preset name

Constant Value: 32 (0x00000020)

## Public constructors

### Equalizer

    public Equalizer (int priority,
                    int audioSession)

Class constructor.

Parameters
`priority` | `int`: the priority level requested by the application for controlling the Equalizer engine. As the same engine can be shared by several applications, this parameter indicates how much the requesting application needs control of effect parameters. The normal priority is 0, above normal is a positive number, below normal a negative number.
`audioSession` | `int`: system wide unique audio session identifier. The Equalizer will be attached to the MediaPlayer or AudioTrack in the same audio session.

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`` | java.lang.RuntimeException
`IllegalArgumentException` |
`IllegalStateException` |
`RuntimeException` |
`UnsupportedOperationException` |

## Public methods

### getBand

    public short getBand (int frequency)

Gets the band that has the most effect on the given frequency.

Parameters
`frequency` | `int`: frequency in milliHertz which is to be equalized via the returned band.

Returns
`short` | the frequency band that has most effect on the given frequency.

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

### getBandFreqRange

    public int[] getBandFreqRange (short band)

Gets the frequency range of the given frequency band.

Parameters
`band` | `short`: frequency band whose frequency range is requested. The numbering of the bands starts from 0 and ends at (number of bands - 1).

Returns
`int[]` | the frequency range in millHertz in an array of integers. The first element is the lower limit of the range, the second element the upper limit.

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

### getBandLevel

    public short getBandLevel (short band)

Gets the gain set for the given equalizer band.

Parameters
`band` | `short`: frequency band whose gain is requested. The numbering of the bands starts from 0 and ends at (number of bands - 1).

Returns
`short` | the gain in millibels of the given band.

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

### getBandLevelRange

    public short[] getBandLevelRange ()

Gets the level range for use by `setBandLevel(short, short)`. The level is expressed in milliBel.

Returns
`short[]` | the band level range in an array of short integers. The first element is the lower limit of the range, the second element the upper limit.

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

### getCenterFreq

    public int getCenterFreq (short band)

Gets the center frequency of the given band.

Parameters
`band` | `short`: frequency band whose center frequency is requested. The numbering of the bands starts from 0 and ends at (number of bands - 1).

Returns
`int` | the center frequency in milliHertz

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

### getCurrentPreset

    public short getCurrentPreset ()

Gets current preset.

Returns
`short` | the preset that is set at the moment.

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

### getNumberOfBands

    public short getNumberOfBands ()

Gets the number of frequency bands supported by the Equalizer engine.

Returns
`short` | the number of bands

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

### getNumberOfPresets

    public short getNumberOfPresets ()

Gets the total number of presets the equalizer supports. The presets will have indices [0, number of presets-1].

Returns
`short` | the number of presets the equalizer supports.

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

### getPresetName

    public String getPresetName (short preset)

Gets the preset name based on the index.

Parameters
`preset` | `short`: index of the preset. The valid range is [0, number of presets-1].

Returns
`String` | a string containing the name of the given preset.

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException

### getProperties

    public Equalizer.Settings getProperties ()

Gets the equalizer properties. This method is useful when a snapshot of current equalizer settings must be saved by the application.

Returns
`Equalizer.Settings` | an Equalizer.Settings object containing all current parameters values

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

### setBandLevel

    public void setBandLevel (short band,
                    short level)

Sets the given equalizer band to the given gain value.

Parameters
`band` | `short`: frequency band that will have the new gain. The numbering of the bands starts from 0 and ends at (number of bands - 1).
`level` | `short`: new gain in millibels that will be set to the given band. getBandLevelRange() will define the maximum and minimum values.

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

See also:

- `getNumberOfBands()`

### setParameterListener

    public void setParameterListener (Equalizer.OnParameterChangeListener listener)

Registers an OnParameterChangeListener interface.

Parameters
`listener` | `Equalizer.OnParameterChangeListener`: OnParameterChangeListener interface registered

### setProperties

    public void setProperties (Equalizer.Settings settings)

Sets the equalizer properties. This method is useful when equalizer settings have to be applied from a previous backup.

Parameters
`settings` | `Equalizer.Settings`: an Equalizer.Settings object containing the properties to apply

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

### usePreset

    public void usePreset (short preset)

Sets the equalizer according to the given preset.

Parameters
`preset` | `short`: new preset that will be taken into use. The valid range is [0, number of presets-1].

Throws
`` | java.lang.IllegalStateException
`` | java.lang.IllegalArgumentException
`` | java.lang.UnsupportedOperationException
`IllegalArgumentException` |
`IllegalStateException` |
`UnsupportedOperationException` |

See also:

- `getNumberOfPresets()`

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